Remove almost all binaries and switch to maven project.

In detail:

* Remove most jar and gem files from build_lib, since they will
  be sourced via maven.
* Remove nbproject and allow NetBeans to open us as a Maven
  project.
* Remove build.xml references to build_lib binaries
* Remove some ant build targets that are no longer used and/or
  will not work without build_lib present.
Remove remaining binaries from build_lib.

* bnd is now sourced from maven.
* bouncy-castle-java.rb moved under gems/bouncy-castle-java/lib.
* jruby-win32-ole gem will get sourced from maven.

Additional tweaks to get jar-dist working.
Eliminate most references to build_lib.
Get dev gems installing properly with removed build_lib.
Move to @mkristian's proposed layout, with some modifications.
Remove Constants.java from src tree.
get the Constants.java updated with each maven run - added missing pom.xml from ext/maven/docs dir
moved deps from jruby-complete to jruby-core so things compile
Fix copying of .rb sources into jar and path to jruby.home.
hack around dep cycle between jruby-core and opensll
Use outputFile in shade, to avoid intermediate original-* jars.
added initial pom for testing
Start getting unit tests running under core.
Merge branch 'stripped_project' of github.com:jruby/jruby into stripped_project
Add Maven Site reporting
[skip ci] CI is on Travis now.
allow File.rename to take path-like arguments
ensure IO.sysopen convert the path-like object to a String before String checks
add Pathname as a hybrid native/ruby library (following MRI)
Merge pull request #854 from jendave/maven-reporting

Add Maven Site reporting